A vibrating plate driven by a frequency in the neighborhood of the resonance frequency of the vibrating plate is very effective for an electronic buzzer. This is especially true if the electronic buzzer is of minature size and should be operated with low power as in an electronic watch.
However, in the conventional electronic buzzer having a single vibrating plate, the frequency band which obtains sufficient sound pressure is very narrow whereby it is necessary to provide an adjusting means for adjusting the driving frequency. Moreover, it is very inconvenient to change the sound tone of the buzzer so as to generate sounds of different types.